Major design flaws have been identified in the Army's new fleet of armoured vehicles.
An internal leaked government report also raises serious doubts as to whether the £5.5bn Ajax Armoured Vehicle programme will be delivered on time and within budget.
Problems include excessive vibration and noise.
The Ministry of Defence signed a contract for 589 of the Ajax armoured vehicles in 2014.
An investigation by the government's Infrastructure and Projects Authority says the "successful delivery of the programme to time, cost and quality appears to be unachievable".
The BBC has seen extracts of the leaked report. It states that compelling evidence was found that the programme will not deliver the planned number of Ajax family armoured fighting vehicles to the British Army for planned operational deployments in 2023/24.